I am talking about the air leaving the rear of the car and tumbling/swirling against rear bumper. i don't really have time to find diagrams. the rear diffuser will not stop the tumbling air if their is no front Aero or underpanels.

RIF:

Great craftsmanship but are either of this functional at all ? Will it rip off at 100+ mph ? Does it actually stop the air exiting the underside of the car from tumbling and swirling, reducing vacuum under the car? Air flowing under the car's front bumper compresses and speeds up to squeeze between the car and the ground. Does thisA diffuser create a tunnel or void in the floorpan that allows air to expand and create a vacuum under the chassis.